Barbara Walters made headlines when she asked that question while interviewing Christie for her “10 Most Fascinating People of 2012” special. The question is fair as it relates to health and presidential politics, although Walters might not be thrilled if someone asked if she’s too old to be on TV.

Christie, who is known for rude replies to questions he doesn’t like, has a touching vulnerability when it comes to the “F” word. He said he didn’t think he’s too fat, adding: “I think people watched me for the last number of weeks during Hurricane Sandy doing 18-hour days and getting back up the next day and still being just as effective in the job, so I don’t think that will be a problem.”

If he truly believes that, he’s not just Jersey strong, he’s Jersey delusional. This country is obsessed with looks and thinness. When it comes to presidential politics, the John F. Kennedy model sets the bar for the modern candidates.

Mitt Romney got as far as he did in 2012 because he looked the part. His flaws, most notably a complete lack of core convictions, eventually caught up with him. But it took awhile for voters to understand how much emptiness came be wrapped in a pretty and physically fit package.

You can be a fat governor like Christie, or a fat speaker of the House like the legendary Tip O’Neill. But a fat president is a tough sell to today’s voters.

When Christie was said to be contemplating a 2012 presidential run, Timothy Noah of the New Republic looked into the topic of presidential girth. He came up with a list of the five fattest presidents compiled by the now-defunct George magazine. Ranked “medically obese” on the basis of their BMI (body mass index), the list, from highest to lowest, included William Howard Taft (1909-1913), Grover Cleveland (1885-1889 and 1893-1897), William McKinley (1897-1901), Zachary Taylor (1849-1850), and Theodore Roosevelt (1901-1909).

Taft was the last “medically obese” president. During his presidency, Bill Clinton was considered medically overweight, but he was much slimmer when seeking votes on the presidential campaign trail.

In the post-Kennedy era, the image of physical fitness increasingly becomes a metaphor for political fitness. In Massachusetts, whenever the late Ted Kennedy dieted, political junkies speculated about his next move.

But looks can also deceive. Images of a tan and graceful JFK do not square with the truth about his health. Ronald Reagan was always chopping wood to offset speculation about what we now know were legitimate questions about the effects of aging. Besides, is the best president the one we could hire as a personal trainer? George W. Bush was a mountain-biking fanatic. A commitment to longer hours of quiet contemplation might have produced more thoughtful policies.

If he stays fat, Christie can expect to be asked about it, and he should be in connection with legitimate health concerns. But focusing on his heft detracts from the real questions about his political future. Unlike Romney, he’s a man of strong conviction and he’s unafraid to say what he believes. In Christie’s case, saying what he believes often comes across as obnoxious and bullying. Before his warm and fuzzy photo-op with Obama, he called the decisions by Atlantic City residents who failed to evacuate “stupid and selfish.”

When Walters asked Christie about his temper, he said, “You know, anger is not a vice. There are times when it’s appropriate for folks to react angrily. And it expresses a particular emotion and point of view that I think is very powerful.”

It’s great to be all bluster and bravado in New Jersey. But how does that translate to a national stage? Telling it like it is feels good, but how does it advance the interests of the country you represent?

Christie is reaping the political benefits of a wise decision to embrace Obama at a time of need. He should not be judged by weight or photo-op alone. Neither gives the full picture of his fitness for higher office.

Joan Vennochi can be reached at vennochi@globe.com. Follow her on Twitter at Joan_Vennochi.